Automatic Street light needs no manual operation for switching ON and OFF when there is
need of light. It detects itself weather there is need for light or not. When darkness rises to a
certain value then automatically street light is switched ON and when there is other source of
light i.e. day time, the street light gets OFF. The sensitiveness of the street light can also be
adjusted. In our project we have used four L.E.D for indication of bulb but for high power
switching one can connect Relay (electromagnetic switch) at the output of pin 3 of I.C 555.
Then it will be possible to turn ON/OFF any electrical appliances connected all the way through
relay.

PRINCIPLE:

This circuit uses a popular timer I.C 555. I.C 555 is connected as comparator with pin-6
connected with positive rail, the output goes high(1) when the trigger pin 2 is at lower then
1/3rd level of the supply voltage. Conversely the output goes low (0) when it is above 1/3rd
level. So small change in the voltage of pin-2 is enough to change the level of output
(pin-3) from 1 to 0 and 0 to 1. The output has only two states high and low and can not remain
in any intermediate stage. It is powered by a 6V battery for portable use. The circuit is
economic in power consumption.
Pin 4, 6 and 8 is connected to the positive supply and pin 1 is grounded.
To detect the present of an object we have used LDR and a source of light. LDR is a
special type of resistance whose value depends on the brightness of the light which is falling
on it. It has resistance of about 1 mega ohm when in total darkness, but a resistance of only
about 5k ohms when brightness illuminated. It responds to a large part of light spectrum.
We have made a potential divider circuit with LDR and 100K variable resistance connected
in series. We know that voltage is directly proportional to conductance so more voltage we will
get from this divider when LDR is getting light and low voltage in darkness. This divided voltage
is given to pin 2 of IC 555. Variable resistance is so adjusted that it crosses potential of 1/3rd
in brightness and fall below 1/3rd in darkness.
Sensitiveness can be adjusted by this variable resistance. As soon as LDR gets dark the
voltage of pin 2 drops1/3rd of the supply voltage and pin 3 gets high and LED or buzzer which
is connected to the output gets activated.

a) Battery: For 9v power supply we can use 6pcs dry cell or 6F22 9v single piece battery.b) Switch: Any general purpose switch can be used. Switch is used as circuit breaker.c) L.D.R: (Light Depending Resistance) it is a special type of resistance whose value
depends on the brightness of light which is falling on it. It has resistance of about 1mega ohm
when in total darkness, but a resistance of only about 5k ohms when brightness illuminated. It
responds to a large part of light spectrum.d) L.E.D: A diode is a component that only allows electricity to flow one way. It can be
thought as a sort of one way street for electrons. Because of this characteristic, dioded are
used to transform or rectify AC voltage into a DC voltage. Diodes have two connections, an
anode and a cathode. The cathode is the end on the schematic with the point of the triangle
pointing towards a line. In other words, the triangle points toward that cathode. The anode is,
of course, the opposite end. Current flows from the anode to the cathode. Light emitting
diodes, or LEDs, differ from regular diodes in that when a voltage is applied, they emit light.
This light can be red (most common), green, yellow, orange, blue (not very common), or infa
red. LEDs are used as indicators, transmitters, etc. Most likely, a LED will never burn out like a
regular lamp will and requires many times less current. Because LEDs act like regular diodes
and will form a short if connected between + and -, a current limiting resistor is used to prevent
that very thing. LEDs may or may not be drawn with the circle surrounding them.e) Variable resistance: (Potentiometer) Resistors are one of the most common
electronic components. A resistor is a device that limits, or resists current. The current limiting
ability or resistance is measured in ohms, represented by the Greek symbol Omega. Variable
resistors (also called potentiometers or just "pots") are resistors that have a variable
resistance. You adjust the resistance by turning a shaft. This shaft moves a wiper across the
actual resistor element. By changing the amounts of resistor between the wiper connection and
the connection (s) to the resistor element, you can change the resistance. You will often see
the resistance of resistors written with K (kilohms) after the number value. This means that
there are that many thousands of ohms. For example, 1K is 1000 ohm, 2K is 2000 ohm, 3.3K is
3300 ohm, etc. You may also see the suffix M (mega ohms). This simply means million.
Resistors are also rated by their power handling capability. This is the amount of heat the
resistor can take before it is destroyed. The power capability is measured in W (watts).
Common wattages for variable resistors are 1/8W, 1/4W, 1/2W and 1W. Anything of a higher
wattage is referred to as a rheostat.f) P.C.B: (Printed Circuit Board) with the help of P.C.B it is easy to assemble circuit with
neat and clean end products. P.C.B is made of bakelite with surface pasted with copper
track-layout. For each components leg, hole is made. Connection pin is passed through the
hole and is soldered.

WORKING:

When light falls on the LDR then its resistance decreases which results in increase of the
voltage at pin 2 of the IC 555. IC 555 has got comparator inbuilt, which compares between the
input voltage from pin2 and 1/3rd of the power supply voltage. When input falls below 1/3rd
then output is set high otherwise it is set low. Since in brightness, input voltage rises so we
obtain no positive voltage at output of pin 3 to drive relay or LED, besides in poor light
condition we get output to energize.

Precautions:

a) LDR used should be sensitive. Before using in the circuit it should be tested with
multimeter.
b) I.C should not be heated much while soldering, too much heat can destroy the I.C. For
safety and easy to replace, use of I.C base is suggested. While placing the I.C pin no 1 should
be made sure at right hole.
c) Opposite polarity of battery can destroy I.C so please check the polarity before
switching ON the circuit. One should use diode in series with switch for safety since diode
allows flowing current in one direction only.
d) L.E.D glows in forward bias only so incorrect polarity of L.E.D will not glow. Out put
voltage of our project is 7.3 volt therefore 3 LED in series can be easily used with out
resistance.
e) Each component should be soldered neat and clean. We should check for any dry
soldered.
f) LDR should be so adjusted that it should not get light from streetlight itself.

Heat Sensor:-Gives tone when there is
change in temperature.
Tips:
* If Thermistor is of PTC type then still you can use it by
interchanging thermistor and 100 Ohms resistance.
* You can use 2 same value thermistor also in place of
replacing 100 Ohms resistance. Then you can use to
compare temperature between two place.
Here is a simple circuit which can be used as a heat
sensor. In the following circuit diagram thermistor and
100 Ohms resistance is connected in series and makes a
potential devider circuit . If thermistor is of N.T.C
(Negative temperature Coefficient ) type then after
heating the thermistor its resistance decreases so more
current flows through the thermistor and 100 Ohms
resistance and we get more voltage at junction of
thermistor and resistance. Suppose after heating 110
ohms thermistor its resistance value become 90 Ohms.
then according to potential devider circuit the voltage
across one resistor equals the ratio of that resistor's
value and the sum of resistances times the voltage
across the series combination. This concept is so
pervasive it has a name: voltage divider.
The input-output relationship for this system, found in
this particular case by voltage divider, takes the form of a
ratio of the output voltage to the input voltage.vout R2 vout 100
-------= -------- => ------- = ------ =>19 vout=90=>vout=4.73vin R1+R2 9 190

This output voltage is applied to a NPN transistor through
a resistance. Emitter voltage is maintain at 4.7 volt with a
help of Zener diode. This voltage we will use as compare
voltage.
NPN transistor conducts when base voltage is greater
than emitter voltage. Transistor conducts as it gets more
than 4.7 base Voltage and circuit is completed through
buzzer and it gives Sound.

HOME
Electronic eye has much use in this electronic age. Also Known as magic eye. It can be used as an automatic guest indicator at the door, If fitted on the bottom of the door entrance. Once it is installed at the door there is no need to install a call bell. It can also be used at homes or in banks as a burglar alarm.
Fix the LDR to the wooden door or a locker to be protected in such a manner that when anybody tries to open it, a shadow falls on the LDR and the circuit gets activated and produce a pleasant sound through the buzzer.
This electronic eye circuit uses NOT gate from CMOS I.C CD 4049. CD 4049 contains 6 independent NOT gate in one package; we have used here (a) one only. NOT gate output goes high(1) when the input pin 3 is at lower then 1/3rd level of the supply voltage. Conversely the output goes low (0) when it is above 1/3rd level. So small change in the voltage of pin-2 is enough to change the level of output (pin-3) from 1 to 0 and 0 to 1. The output has only two states high and low and can not remain in any intermediate stage. It is powered by a 9V battery for portable use. The circuit is economic in power consumption. Pin 1 is connected to the positive supply and pin 8 is grounded.
To detect the present of an object we have used LDR and a source of light. LDR is a special type of resistance whose value depends on the brightness of the light which is falling on it. It has resistance of about 1 mega ohm when in total darkness, but a resistance of only about 5k ohms when brightness illuminated. It responds to a large part of light spectrum.
We have made a potential divider circuit with LDR and 220 KΩ resistance connected in series. We know that voltage is directly proportional to conductance so more voltage we will get from this divider when LDR is getting light and low voltage in darkness. This divided voltage is given to input of NOT gate.
As soon as LDR gets dark the voltage of input not gate drops 1/3rd of the supply voltage and pin 2 gets high and LED or buzzer which is connected to the output gets activated.
Advantage of using Logic gate is that data can be easily send to other digital interface device ie one can easily fed data to computer using parallel port or for further processing .

This projects is designed to monitor all incoming and outgoing calls from your landline telephone, and each calls it also sends to pc for logging you can detect any misuse of your telephone line just connect this device in parallel to your telephone line . silently this device will keep doing its job . you can develop pc based software to put time stamp on each call .police department and hospitals can trace any panic call and take necessary action.

Infrared Remote Control Software
This Infrared Remote Control Software project based on Microchip 16C57 microcontroller is a reference guide to decode infrared remote control signals from television, VCR, air conditioner or other home appliances handset that uses NEC 6121 infrared format. Once one is able to understand how to decode an IR signal of a certain format, decoding another format can be easily done as the flow chart is more or less the same except the timing of the new format.
The NEC 6121 format is based on pulse width timing in determining whether the data transmitted is "1" or "0". The data "1" is determined by the pulse width timing from one rising edge to the next rising edge of 2.24ms. The data "0" is determined by the pulse width timing from one rising edge to the next rising edge of 1.12ms.
Most of the transmitter are modulated using a frequency of 32.75 kHz, 35.0 kHz, 36.0 kHz, 36.7 kHz, 38 kHz, 39 kHz, 40 kHz, 41.7 kHz, 48 kHz, and 56.8 kHz. The ones that are commonly used are 38 kHz and 40 kHz. In order to decode the received signals, the corresponding demodulating receiver must be used. For instance, if a modulating frequency at the transmitter used is 40 kHz, then the receiver demodulating frequency used should be 40 kHz as well. Modulating the data is a better design as this will make the data integrity better and less susceptible to noise. The demodulating receivers can be obtained from suppliers such as Vishay, LiteOn, Sharp or Kodenshi.

One word of caution when using the IR remote control is that it is easily affected by lighting devices that emits the infrared frequency. One such example is the fluorescent tube which emits the infrared frequency in its operation. When this type of lights is operating, the receiver may not be able to receive the signal from the transmtter due to interference from the signals emitted by the flurescent tube. In situation like this, confirm this by switching off the lights when controlling the device.
You may want to consider using RF frequency as a solution in this particular location. Another way is to place a filter in front of the receiver to narrow the infrared window but this solution will compromise the angle and operating distance of the infrared transmitter.
The infrared remote control software project provides the flow chart and source code and can be downloaded from Microchip website.

Battery Tester Project Using LM3914 IC
This objective of this project is to design and build a battery tester that is able to test various types of dry cell and rechargable battery with a voltage of less than 2V. Configured as a bar graph battery level indicator, the LM3914 IC from National Semiconductor senses the voltage levels of the battery under test and drives the 10 LEDs to ON or OFF based on the voltage that is detected. The current driving the LEDs is regulated by using the external resistor R1 and hence limiting resistors are not required.
The schematic shows the simple connections where the reference voltage at pin 8 of U1 can be adjusted by adjusting the variable resistor VR1. The voltage at pin 8 will set the maximum scale of the LED. In testing dry cell battery of 1.5V, set the voltage at pin 8 to 2.0V. Each of the LED will thus represent 200mV when lighted up.

If testing of rechargable battery such as NiCd or NiMH is required, set the reference voltage to a lower value such as 1.5V as the typical voltage of a rechargable battery is approximately 1.2V.
When testing the battery, take note of the polarity of the probe to the terminals of the battery. T1 is to be placed on the positive terminal and T2 the negative terminal of the battery.

I really like the Radio Shack boards that are laid out like a solderless breadboard. This is a “game show” style controller produced for a client with a Basic Stamp. The only downside to these boards is that they are one sided and the copper will very easily delaminate if you get it too hot.Another client project, this one is an H-bridge for motor control, driven by a Basic Stamp and PAK PWM controller.A board to control HVAC equipment.

This StarFire board (bare and assembled) was a PIC processor used to gather, store, and transmit model rocketry telemetry. I volunteer with a group that lets high school kids learn about engineering by building quite large rockets. The PIC is riding in a socket that allows an in circuit emulator to attach. Note the two RS-1 serial boards attached to produce RS232 ports. One was socketed, so the board could hook to a PC during development, but a TTL-level GPS in flight, if I recall.

Here is a simple audio amplifier using a TL431 shunt regulator. The amplifier will provide room-filling volume from an ordinary crystal radio outfitted with a long-wire antenna and good ground. The circuitry is similar in complexity to a simple one-transistor radio but the performance is superior (with the exception of the amazing one-transistor reflex ). The TL431 is available in a TO-92 package and it looks like an ordinary transistor so your hobbyist friends will be impressed by the volume you are getting with only one transistor and the amplifier may be used for other projects, too. Higher impedance headphones and speakers may also be used.